1. Technical Field
Embodiments of the invention relate generally to thermal engines, such as diesel engines. Particular embodiments relate to fluid heat exchange systems for turbocharged or supercharged diesel engines.
2. Discussion of Art
Diesel engines are used in various transportation applications, for example, in propulsion of marine vessels. Often, such engines use turbochargers or superchargers to scavenge exhaust gas pressure for pressurizing (“charging”) intake air. Typically, engines that use chargers also include a charge air cooler for reducing the temperature of the pressurized air before it is introduced into the combustion cylinders. The charge air coolers typically house water coils; the high temperature charge air flows across fins mounted to those water coils, while the water through those coils flows to a fin-tube heat exchanger cooled by water. Additionally, diesel engines typically are cooled directly by water flowing through internal passages, and indirectly by lubricating oil that coats and flows between moving parts.
Commonly, each cooling system (charge air cooler, cooling water, and oil cooling) has its own set of piping and valves. Packaging all this piping into a smallest feasible volume produces a tangle of metal parts that presents challenges for assembly, inspection, and maintenance of key components such as thermostat valves, pumps, sensors etc.
For example, each cooling system comprises a thermostat mixing or diverging valve, which regulates temperature at the hot side of the coolant loop by adjusting the proportion of coolant that flows through or bypasses the cool side of the loop. Usually, the thermostat valves and other components are accessible for inspection or maintenance only by removing a substantial mass of piping.
An additional characteristic of the typical tangle of coolant and lubricant piping is that certain components or joints within this tangle are relatively flexible and, therefore, have relatively low natural frequencies which are less than engine running frequency, leading to resonance or excessive vibrations. Thus, at typical engine running speeds, excitation of a single component or joint can lead to adverse vibration of the entire piping system.